This invention relates generally to haptic feedback devices, and more particularly to haptic feedback interface devices used in conjunction with mechanical devices allowing desired manipulation of the interface device.
Control of a vehicle through the use of electronically-controlled mechanisms rather than mechanically-controlled mechanisms has been implemented in several different forms. Typically called “steer-by-wire,” “drive-by-wire,” or “control-by-wire”, this form of control allows the user to direct electric motors and/or hydraulic or pneumatic control systems, to perform mechanical operations rather than the user directly performing the mechanical operations using a mechanism. For example, in a standard mechanical steering mechanism in an automobile, the user moves a steering wheel, which mechanically rotates rods, gears, and other mechanical parts to turn the front wheels based on the motion of the steering wheel. In a drive-by-wire system, the user rotates the steering wheel (or moves some other type of manipulandum), which controls one or more electric motors, hydraulic actuators, etc., to turn the front wheels based on steering wheel motion—there is no actual mechanical linkage between steering wheel motion and wheel motion (unlike power assisted steering). A processor (microprocessor, etc.) can be used to sense user motion and correlate it with motor control to achieve the corresponding steering. There are several advantages of control-by-wire over traditional mechanical control, including safety, since there is no mechanism to injure the user; less effort or force required by the user to manipulate the control device; more flexibility in type and motion of the control device used and in the control methods over the mechanism; less weight for the mechanism; less skill required by the user in performing control tasks since a control processor can translate simple user motions into the complex control of motors needed to perform the desired mechanical action; engineering advantages (e.g., it is easier to put a steering wheel in either side of a car when using steer-by-wire); and the use of control methods such as adaptive steering algorithms.
A related control-by-wire embodiment is “shift-by-wire,” in which an automobile or other vehicle having a driving transmission is shifted through its transmission gears using electronic control rather than direct mechanical control. Thus, instead of the user moving a shift lever to predetermined mechanical positions to mechanically change gears, the user can manipulate an electronic control and the electronic system can change the actual transmission gears. For example, the user can move a small lever forward to increase a gear ratio (e.g., from first gear to second gear), or move the lever backward to decrease the gear ratio (e.g., from fifth gear to fourth gear). A variety of different electronic controls can be used in the vehicle to allow the user to shift, such as levers, buttons, knobs, switches, etc.
One problem with existing shift-by-wire systems is that they are still limited to a particular implementation of the physical control manipulated by the user. That is, the user cannot change to a different shift pattern if he or she so desires. Furthermore, shift-by-wire controls do not offer the user some of the cues of mechanical systems in controlling shifting, which may cause the control to be unintuitive or less precise. Since shifting is performed almost entirely by feel, such mechanical cues can be important in shifting tasks.